Material treating apparatus

ABSTRACT

Apparatus for treating, especially drying or humidifying, tobacco or like material comprises a rotating drum inclined to the horizontal and fitted with longitudinally-extending internal shelves so that material placed in the drum is repeatedly lifted by the shelves and dropped as the shelves tilt with drum rotation, the material simultaneously progressing towards the lower end of the drum. Within the drum, one or more stationary guides are disposed to catch material falling from the selected upper area of the drum and guide it towards the higher end, the arrangement being such that moister material is so caught while drier material falls clear of the guides.

United tates tent 1191 ,1 awor 1451 .Bune4,1974

[ MATERIAL TREATING APPARATUS [75] Inventor: Tadeusz Bronislaw Jawor, London,

England [73] Assignee: Molins Machines Company Limited, London, England 22 Filed: Mar. 14,1972

211 Appl. No: 234,565

Related U.S. Application Data [63] Continuation of Ser. No. 61,152, Aug. 5, 1970,

abandoned.

[52] 11.5. C1 34/136, 34/108, 34/134 [51] llnt. C1. F26g 11/04 [58] Field of Search 34/108, 109, 115, 135,

[56] References Cited UNITED STATES PATENTS 1,160,109 11/1915 Henrici 34/109 X 2.728.146 12/1955 Cody 34/109 3,245,154 4/1966 Bovner et a1. 34/137 X Camm 34/ l 09 Thompson 34/136 Primary Examiner-Char1es .1. Myhre Assistant ExaminerTheophil W. Streule, Jr. Attorney, Agent, or Firm-Markva & Smith [57] ABSTRACT Apparatus for treating, especially drying or humidifying, tobacco or like material comprises a rotating drum inclined to the horizontal and fitted with longitudinally-extending internal shelves so that material placed in the drum is repeatedly lifted by the shelves and dropped as the shelves tilt with drum rotation, the material simultaneously progressing towards the lower end of the drum. Within the drum, one or more stationary guides are disposed to catch material falling from the selected upper area of the drum and guide it towards the higher end, the arrangement being such that moister material is so caught while drier material falls clear of the guides.

15 Claims, 3 Drawing Figures PATENTEDJUH 19M v 11813794 fwywmm v Afforne MATERTAL TREATING APPARATUS This is a continuation of application Ser. No. 61,152, filed Aug. 5, 1970, now abandoned.

This invention relates to apparatus for treating tobacco and like material, e.g., dying or humidifying apparatus.

It is common for tobacco drying apparatus to comprise a heated drum, mounted rotatably and inclined to the horizontal, the material to be dried being fed into the higher end of the drum and travelling down to the lower end as the drum rotates. Longitudinallyextending ribs or shelves on the interior surface of the drum increase the area of heated surface to which the material is exposed; as material falls to the lower part of the drum the ribs or shelves cause it to travel round with the rotation of the drum until it can fall clear of the ribs or shelves, returning to the lower part of the drum whereupon this process is repeated. The drying of the material is commonly assisted by blowing hot dry air through the drum in the opposite direction to the travel of the material to be dried, i.e. blowing said air from the lower end of the drum towards its higher end.

Such apparatus, however, does not give such efficient drying as is desirable with many materials. In particular, cut tobacco comprises a mixture of fibres of different lengths and thicknesses, and it will readily be appreciated that the thicker fibres need to spend a longer time in the drum than do the thinner fibres, if a substantially uniform moisture content is desired in all the fibres upon leaving the drum.

It is an object of the invention to provide an improved form of drying apparatus for material such as tobacco, enabling a greater uniformity of drying to be attained.

According to the invention, there is provided apparatus for treating material such as tobacco, comprising a drum which has longitudinally-extending internal shelves and is rotatably mounted with its longitudinal axis inclined to the horizontal, so that rotation of the drum tends to cause material therein to move from the higher end of said drum towards its lower end, and means for rotating said drum about said axis, in which at least one stationary guide is provided within said drum, said guide being mounted at such an inclination that its upper end is nearer to the lower end of the drum than to the higher end of the drum and being so dimensioned and positioned as to intercept material falling from a selected upper region of said drum and guide such material towards the higher end of said drum as said material completes its descent.

The operation of such apparatus depends upon the fact that with a material such as tobacco, the higher the moisture content the greater is the frictional resistance of the material to sliding over a smooth surface; more conveniently expressed for present purposes, the greater its friction angle" that is, the greater the angle to which a surface carrying the material can be tilted before the material starts to slide.

Applying this fact to the treatment of cut tobacco in an apparatus embodying the invention, as above defined, as each of the internal shelves rises up one side of the drum as the latter revolves, the shelf will be carrying tobacco on its upper surface and the tilt of that surface will be changing as the drum revolves. Assuming that the shelf extends radially of the drum then during of rotation of the drum immediately after the shelf being considered has passed through its lowermost position the inclination of the shelf will be such that there is no tendency for tobacco to slide off it. However, as soon as this 90 of rotation is complete, further rotation of the drum causes the shelf to be tilted increasingly in a sense in which the tobacco can slide off, and when the angle of tilt of any shelf passes the friction angle for the tobacco on that shelf, that tobacco will slide off the shelf and fall to the lower regions of the drum. As the change of tilt of each shelf is due to the rotation of the drum, it will be appreciated that the lateral position at which any particular portion of tobacco leaves the shelf carrying it depends upon its moisture content. The inclined guide is so positioned laterally of the drum that it does not lie in the path of the driest tobacco, but the tobacco with the greatest moisture content, which requires a greater tilt of the shelf before it slides off, is carried above the guide before it leaves the shelf. Accordingly, the latter tobacco when it falls off the shelf reaches the guide and slides down the guide to reach the lower regions of the drum. In doing so, it is deflected back towards the higher end of the drum and away from the lower end of the drum, i.e. the material is moved in'the opposite sense to the motion of material falling clear of the guide.

Thus if the tobacco is fed into the higher end of the drum and discharged from its lower end, the moister tobacco is caused to spend a longer time in the drum than the drier tobacco; this is what is required when apparatus embodying the invention is employed for drying tobacco,'the drum and the guide or guides then being heated and hot air being blown through the drum. if on the other hand apparatus embodying the invention is required for use in humidifying tobacco, when the tobacco is fed into the lower end of the drum and discharged from its higher end; with this arrangement the drier tobacco spends a longer time in the drum than does the moister tobacco. In the latter case, also, it is necessary to arrange the guide or guides to extend over the whole length of the drum, with overlap between adjacent guides if more than one guide is provided, as it is only on the guide or guides that the tobacco feeds towards the higher end of the drum, which in" this case is the desired direction of feed.

In drying apparatus embodying the invention, it is preferred to provide more than one guide, for example three guides may be provided at different positions longitudinally of the drum. When more than one guide is provided, it will be understood that each of such guides must be differently positioned, laterally of the drum, or alternatively the angle of the shelves relative to the drum must be different at different positions along the length of the drum, i.e. in the vicinity of the different guides, as if the guides were all identically positioned and the angle of the shelves was uniform along the length of the drum, then only the first guide would perform any significant function, as any tobacco which was sufficiently dried to fall clear of the first guide must also fall clear of the other guides.

In order that the invention may be fully understood, a preferred embodiment thereof will now be described in more detail, referring to the accompanying drawings in which:

FIG. 1 is a side view, partly in elevation and partly in section, of a tobacco drying apparatus embodying the invention; and

FIGS. 2 and 3 are both cross-sections on line IIII of FIG. 1, but with parts in slightly different positions.

It will be appreciated that the drawings are somewhat diagrammatic in nature, so that significant features are not obscured by conventional details of structure.

As shown in the drawings, a drying apparatus for tobacco comprises a cylindrical drum generally indicated at 1 and having an outer wall 2 and an inner wall 3. In operation, steam and/or hot air is blown through the space between said inner and outer walls to maintain the interior of the drum at a desired temperature. I-Iot air is also blown through the interior of the drum, from right to left as seen in FIG. l.

The drum 1 is rotatably mounted in journal bearings (not shown) at its ends, and is held at a small angle to the horizontal, indicated as angle A in FIG. ll. Tobacco to be dried is fed into the higher end of the drum l (the lefthand end as seen in FIG. I) and after drying is discharged from the lower end of the drum ll (right-hand end as seen in FIG. I).

The inner surface of the inner wall 3 carries a number of projecting shelves 4 as shown, there are eight of these shelves 4. As can be seen in FIGS. 2 and 3, the shelves 4 do not extend radially of the drum 1, but are inclined forward relative to the direction of rotation of the drum 1, which direction of rotation is, as indicated by the arrow 5, anti-clockwise as seen in FIGS. 2 and 3 (FIG. 3 shows the drum in a slightly different rotational position from that shown in FIG. 2). On the rear face of each shelf 4, as considered relative to its direction of motion, are secured three heating elements 6. These heating elements 6 may be pipes carrying steam of heated air, or may be electric heating elements.

Through the interior of the drum ll extend three stationary support bars 7, and secured to these bars 7 at intervals are three guides 8. Each of the guides 8 comprises a slightly curved plate, the curvature being substantially cylindrical, and each guide 8 is inclined to the horizontal as best seen in FIG. I, its upper end being nearer to the lower (discharge) end of the drum ll, i.e., the right hand end of the drum II as seen in FIG. ll.

Preferably the guides 8 are hollow and the support bars 7 are pipes carrying steam and/or hot air to the interior of the guides 8 to keep the later at a desired temperature.

In operation, the drum l is rotated, its direction of rotation being, as previously mentioned, anti-clockwise as viewed in FIGS. 2 and 3 and tobacco for drying is supplied to the higher end of the drum ll i.e., the lefthand end as seen in FIG. I and travels along the length of the drum 1 for discharge from its lower end. The tobacco travels along the drum because it first falls on the inside surface of the inner wall 3 and, because of the presence of the shelves 4, is carried around the drum as the latter rotates, until the tobacco falls back towards the lower part of the drum and is again carried around with the shelves 3 until it falls again. Because of the inclination of the drum 1, each time the tobacco is carried round with the shelves 4, it also moves a short distance to the right as seen in FIG. I and hence the to bacco moves, in steps, towards the lower end of the drum. This continued 37 tumbling of the tobacco also exposes it effectively to the hot air stream blowing through the drum.

When tobacco travelling along the drum 1 reaches the vicinity of one of the guides 8, the path of the tobacco depends upon its moisture content. As mentioned above, the frictional resistance of the tobacco to sliding motion over a smooth surface varies with its moisture content, being greater when the tobacco is moist than when it is dry. When, therefore, one of the shelves 4, upon which tobacco is resting, reaches a position in alignment with the arrow X (FIG. 2) that shelf is so inclined that if it is carrying relatively dry tobacco then the tobacco tends to slide off it and it can be seen from FIG. 2 that tobacco leaving the shelf 4 at this stage will fall to the bottom of the drum. However, if the shelf is carrying moister tobacco a greater tilt of the shelf 4 is required before it slides off the shelf, and if the tobacco is sufficiently moist to stay on the shelf until it reaches a position in alignment with the arrow Y (FIG. 3) then it will be seen that the tobacco upon leaving said shelf will fall upon one of the guides 8. The guides 8 are inclined at a sufficient angle for the tobacco thus reaching them to slidedown, but because of the positioning of the guides 8, such tobacco will, as it is descending the guide, also move back towards the higher end of the drum 1, i.e., the left-hand end as seen in FIG. 1. This moister tobacco, therefore, having reached a particular position along the length of the drum 1, will be guided back a certain distance along the drum and will have to travel forward again past a position it has previously reached before it can proceed further towards the discharge end of the drum 1. This moister tobacco is therefore compelled to remain within the drum 1 for a longer time than the drier tobacco which did not travel down the guide 8. It will be appreciated that very moist tobacco may be thus turned back more than once in the vicinity of any one of the guides 8. In fact, before a portion of tobacco can move completely past the vicinity of any one of the guides 8, its moisture content must be brought down to below a certain determined level, as so long as it moisture content remains above that level, it will be repeatedly caused to fall upon the guide 8 and returned to a position further away from the discharge end of the drum ll.

As a practical matter, the performance of the apparatus is not as exact as just explained as it is obviously possible for a relatively moist portion of tobacco to rest upon a drier portion of tobacco which in turn rests upon one of the shelves 4 as the latter ascends with the rotation of the drum 1, and in such circumstances the moist tobacco will tend to slide off the shelf and fall clear of the guides 8 because it is the underlying drier tobacco which is actually in contact with the shelf 4.

However, although this may happen once, as the tobacco is falling it is likely to separate and there is only a small probability that this particular portion of moist tobacco will again be resting upon drier tobacco as it reaches the vicinity of the next following guide 8.

If the guides 8 were all identically positioned in the cross-section of the drum 1 and the tilt of the shelves 4 was uniform throughout their length, then it will be apparent that only the first guide 8 (i.e., the left-hand one of the three guides, as seen in FIG. 1) would be fully effective. However, as can be seen from the drawings, the forward inclination (relative to the direction of rotation) of the shelves 4 is increased progressively from the higher to the lower (discharge) end of the drum 1. From this it follows that some of the tobacco which, in the vicinity of the first of the guides 8, falls clear of said guide when it reaches the vicinity of the second or the third guide it will be carried sufficiently high to fall upon that guide with the consequences explained above. In other words, by increasing the tilt of the shelves 4 towards the lower end of the drum 1 the level of moisture content at which the tobacco is caused to fall upon the guide 8 is lowered and thus all three of the guides 8 are effectively employed.

The actual positioning of the guides 8 and the angle of tilt of the shelves at various positions along the length of the drum ll depend upon the material being dried and the material out of which the shelves 4 are manufactured. As an illustrative example, it may be mentioned that on a rolled brass surface, Virginia tobacco has a friction angle of 27 when it has l2 percent moisture content, but this friction angle rises to 30 for percent moisture content and to 41 for 19 percent moisture content.

Various modifications or charges are possible in the details of the apparatus described without departing from the scope of the invention. For example, the guides 8 may be heated more directly by passing an electric current through the actual material of the guides, which are then of course made of material of suitable electrical resistivity.

I claim:

l. Apparatus for treating particulate material, such as drying or humidifying tobacco, to produce material having a predetermined condition, comprising a. a drum mounted for rotation about an axis inclined to the horizontal whereby rotation of the drum causes said material contained therein to move from the higher end of the drum to its lower end,

b. at least one generally longitudinally extending shelf mounted on the interior wall of said drum to repeatedly collect said material and convey said material upwardly along a cylindrical path until said material freely falls from said shelf under the influence of gravity during rotation of said drum, the location along said cylindrical path at which said material falls depending upon the condition of said material,

c. at least one stationary guide within said drum, said guide being mounted in a position substantially inclined to the horizontal with its upper end nearer to the lower end of the drum than to the higher end of the drum to selectively intercept material falling from said shelf at a predetermined location along said cylindrical path and guide the intercepted ma terial towards the higher end of said drum as said material completes its descent,

d. whereby movement of material through said drum takes different times for material which is intercepted during its descent and material which is not so intercepted, the time taken by any particular material corresponding to the location at which that material falls off the shelf and hence upon the condition of that material.

2. Apparatus as claimed in claim 1, in which each of said internal shelves is inclined forward relative to the direction of rotation of the drum,

3. Apparatus as claimed in claim 2, in which the forward inclination of said shelves increases progressively from the higher to the lower end of the drum.

4. Apparatus as claimed in claim 3, in which each of the shelves is provided with heating means.

5. Apparatus as claimed in claim 4 in which heating pipes are secured to the rear face of each shelf considering the direction of rotation.

6. Apparatus as claimed in claim 4, in which electric heating elements are secured to the rear face of each shelf considering the direction of rotation.

'7. Apparatus as claimed in claim 1, in which each guide is provided with heating means.

8. Apparatus as claimed in claim 1, including a plurality of stationary support bars extending through the drum, each being secured to said support bars.

9. Apparatus as claimed in claim 8, in which each guide is hollow and said support bars are pipes for carrying hot fluid to the interior of each guide.

110. Apparatus as claimed in claim 1, in which the drum has inner and outer walls between which hot fluid may be circulated.

lll. Apparatus for treating particulate material, such as drying or humidifying tobacco, to produce material having a predetermined condition comprising:

a. conveyor means having inlet and outlet ends at different levels so as to define an inclined path for material from said inlet end to said outlet end,

b. at least one elevating means having a material supporting surface mounted for continuous movement along a closed path transverse to and intersecting said inclined path at the lowermost point in said closed path to repeatedly collect on said supporting surface said particulate material from said inclined path and convey said material upwardly along part of said closed path, with progressively increasing tilting of said supporting surface as said elevating means passes through a plurality of zones along said closed path above said inclined path to cause said material to slide off said supporting surface as it passes through one of said plurality of zones and freely descend under the influence of gravity toward said inclined path whereby the particular zone at which said material slides off said supporting surface is dependent upon the condition of said material, and

c. stationary guide means substantially inclined to the horizontal with its upper end towards the lower end of said conveyor means and its lower end towards the higher end of said conveyor means, said stationary guide means being positioned to selectively intercept material descending from a predetermined one of said zones along said closed path and to direct the intercepted material towards the higher end of said conveyor means,

whereby movement of material along said inclined path from said inlet end to said outlet end takes different times for material which is intercepted during descent and material which is not so intercepted, the time taken by any particular material corresponding to the zone in which that material slides off the supporting surface and hence upon the condition of that material.

12. Apparatus as claimed in claim 11 wherein said elevating means is mounted for continuous movement along a circular path.

13. Apparatus as claimed in claim 12 wherein said conveyor means comprises a drum mounted for rotation about an inclined axis parallel to said inclined path.

14. Apparatus as claimed in claim 13 wherein said elevating means comprises a plurality of longitudinally extending shelves mounted on the interior of said drum.

15. Apparatus as claimed in claim 13 wherein said guide means comprises a plurality of stationary guides spaced from each other within said drum, each said conveyor means. 

1. Apparatus for treating particulate material, such as drying or humidifying tobacco, to produce material having a predetermined condition, comprising a. a drum mounted for rotation about an axis inclined to the horizontal whereby rotation of the drum causes said material contained therein to move from the higher end of the drum to its lower end, b. at least one generally longitudinally extending shelf mounted on the interior wall of said drum to repeatedly collect said material and convey said material upwardly along a cylindrical path until said material freely falls from said shelf under the influence of gravity during rotation of said drum, the location along said cylindrical path at which said material falls depending upon the condition of said material, c. at least one stationary guide within said drum, said guide being mounted in a position substantially inclined to the horizontal with its upper end nearer to the lower end of the drum than to the higher end of the drum to selectively intercept material falling from said shelf at a predetermined location along said cylindrical path and guide the intercepted material towards the higher end of said drum as said material completes its descent, d. whereby movement of material through said drum takes different times for material which is intercepted during its descent and material which is not so intercepted, the time taken by any particular material corresponding to the location at which that material falls off the shelf and hence upon the condition of that material.
 2. Apparatus as claimed in claim 1, in which each of said internal shelves is inclined forward relative to the direction of rotation of the drum.
 3. Apparatus as claimed in claim 2, in which the forward inclination of said shelves increases progressively from the higher to the lower end of the drum.
 4. Apparatus as claimed in claim 3, in which each of the shelves is provided with heating means.
 5. Apparatus as claimed in claim 4 in which heating pipes are secured to the rear face of each shelf considering the direction of rotation.
 6. Apparatus as claimed in claim 4, in which electric heating elements are secured to the rear face of each shelf considering the direction of rotation.
 7. Apparatus as claimed in claim 1, in which each guide is provided with heating means.
 8. Apparatus as claimed in claim 1, including a plurality of stationary support bars extending through the drum, each being secured to said support bars.
 9. Apparatus as claimed in claim 8, in which each guide is hollow and said support bars are pipes for carrying hot fluid to the interior of each guide.
 10. Apparatus as claimed in claim 1, in which the drum has inner and outer walls between which hot fluid may be circulated.
 11. Apparatus for treating particulate material, such as drying or humidifying tobacco, to produce material having a predetermined condition comprising: a. conveyor means having inlet and outlet ends at different levels so as to define an inclined path for material from said inlet end to said outlet end, b. at least one elevating means having a material supporting surface mounted for continuous movement along a closed path transverse to and intersecting said inclined path at the lowermost point in said cLosed path to repeatedly collect on said supporting surface said particulate material from said inclined path and convey said material upwardly along part of said closed path, with progressively increasing tilting of said supporting surface as said elevating means passes through a plurality of zones along said closed path above said inclined path to cause said material to slide off said supporting surface as it passes through one of said plurality of zones and freely descend under the influence of gravity toward said inclined path whereby the particular zone at which said material slides off said supporting surface is dependent upon the condition of said material, and c. stationary guide means substantially inclined to the horizontal with its upper end towards the lower end of said conveyor means and its lower end towards the higher end of said conveyor means, said stationary guide means being positioned to selectively intercept material descending from a predetermined one of said zones along said closed path and to direct the intercepted material towards the higher end of said conveyor means, d. whereby movement of material along said inclined path from said inlet end to said outlet end takes different times for material which is intercepted during descent and material which is not so intercepted, the time taken by any particular material corresponding to the zone in which that material slides off the supporting surface and hence upon the condition of that material.
 12. Apparatus as claimed in claim 11 wherein said elevating means is mounted for continuous movement along a circular path.
 13. Apparatus as claimed in claim 12 wherein said conveyor means comprises a drum mounted for rotation about an inclined axis parallel to said inclined path.
 14. Apparatus as claimed in claim 13 wherein said elevating means comprises a plurality of longitudinally extending shelves mounted on the interior of said drum.
 15. Apparatus as claimed in claim 13 wherein said guide means comprises a plurality of stationary guides spaced from each other within said drum, each said guide being substantially inclined to the horizontal with its upper end towards the lower end of said conveyor means and its lower end towards the higher end of said conveyor means. 